// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_QUIC_QUIC_DATA_WRITER_H_
#define NET_QUIC_QUIC_DATA_WRITER_H_

#include <stddef.h>
#include <stdint.h>

#include <cstddef>
#include <string>

#include "base/logging.h"
#include "base/macros.h"
#include "base/strings/string_piece.h"
#include "net/base/int128.h"
#include "net/base/net_export.h"
#include "net/quic/quic_protocol.h"

namespace net {

// This class provides facilities for packing QUIC data.
//
// The QuicDataWriter supports appending primitive values (int, string, etc)
// to a frame instance.  The internal memory buffer is exposed as the "data"
// of the QuicDataWriter.
class NET_EXPORT_PRIVATE QuicDataWriter {
public:
    // Creates a QuicDataWriter where |buffer| is not owned.
    QuicDataWriter(size_t size, char* buffer);

    ~QuicDataWriter();

    // Returns the size of the QuicDataWriter's data.
    size_t length() const { return length_; }

    // Retrieves the buffer from the QuicDataWriter without changing ownership.
    char* data();

    // Methods for adding to the payload.  These values are appended to the end
    // of the QuicDataWriter payload. Note - binary integers are written in
    // host byte order (little endian) not network byte order (big endian).
    bool WriteUInt8(uint8_t value);
    bool WriteUInt16(uint16_t value);
    bool WriteUInt32(uint32_t value);
    bool WriteUInt48(uint64_t value);
    bool WriteUInt64(uint64_t value);
    // Write unsigned floating point corresponding to the value. Large values are
    // clamped to the maximum representable (kUFloat16MaxValue). Values that can
    // not be represented directly are rounded down.
    bool WriteUFloat16(uint64_t value);
    bool WriteStringPiece16(base::StringPiece val);
    bool WriteBytes(const void* data, size_t data_len);
    bool WriteRepeatedByte(uint8_t byte, size_t count);
    // Fills the remaining buffer with null characters.
    void WritePadding();

    size_t capacity() const { return capacity_; }

private:
    // Returns the location that the data should be written at, or nullptr if
    // there is not enough room. Call EndWrite with the returned offset and the
    // given length to pad out for the next write.
    char* BeginWrite(size_t length);

    char* buffer_;
    size_t capacity_; // Allocation size of payload (or -1 if buffer is const).
    size_t length_; // Current length of the buffer.

    DISALLOW_COPY_AND_ASSIGN(QuicDataWriter);
};

} // namespace net

#endif // NET_QUIC_QUIC_DATA_WRITER_H_
